
/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 17655
 * Date: 2025-08-11
 * Time: 21:54
 */
public class test1 {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode pre = new ListNode(0);
        // 表示进位
        int carry = 0;
        ListNode cur = pre;

        while(l1!=null && l2!=null){
            int x = l1==null?0:l1.val;
            int y = l2==null?0:l2.val;
            int sum = x + y + carry;
            // 更新进位数
            carry = sum/10;
            sum = sum%10;
            cur.next = new ListNode(sum);
            cur = cur.next;
            if(l1!=null){
                l1 = l1.next;
            }
            if(l2!=null){
                l2 = l2.next;
            }
        }
        // 可能会出现600+600的情况
        if(carry==1){
            cur.next = new ListNode(carry);
        }
        return pre.next;
    }


    class ListNode{
        int val;
        ListNode next;

        public ListNode(int val){
            this.val = val;
        }
    }
}
